Well, it's certainly possible that had historical actors made different choices, historical events may have unfolded differently. History, after all, is never inevitable. But I think it's worth breaking down the possibilities that you put forward to explain why they would have been unlikely.

Firstly, abolitionist intensity: today many of us with some familiarity with 19th century history remember some famous abolitionists with a great deal of admiration. Men like Frederick Douglass and William Lloyd Garrison. Women like Harriet Tubman and Harriet Jacobs. They're famed and admired for good reason! All of them courageously advocated the cause of human freedom, at serious risk to themselves (Douglass, Tubman, and Jacobs had all emancipated themselves from slavery, risking torture and death in the process and risking recapture by publicizing their experiences, even the freeborn white Garrison faced the threat of vigilante terrorism). They were also completely unsparing in their condemnation of slavery and slaveholders. Garrison, whose politics may have been the least practical and most radical of the famous abolitionists, was advocating secession long before the South ever went through with it, only he felt that the North should secede from an inherently illegitimate constitution that shamefully protected slavery.

Strident and radical as the critiques of such abolitionists were, they represented the views of a minority of abolitionist activists, who themselves represented only a minority of the Northern population. Most abolitionists, at least before 1860 or so, favored gradual emancipation with compensation for slaveholders (bear this in mind when I discuss southern intransigence later). They also had little interest in black civil rights or racial equality, with most (even Lincoln until 1862!) favoring the "colonization" of emancipated black people in Sierra Leone or Liberia (several thousand free black Americans actually did emigrate to Liberia in the antebellum period, but that's a story for a different post). Most white northerners were quite racist and saw little reason to sympathize with the plight of the millions of enslaved workers in the South. Many urban northerners were actively hostile to emancipation both out of racism and a fear of competition from free black labor (based on the logic that they would, once emancipated, flood northern cities and take jobs from white laborers by being willing to work for lower pay).

You might wonder, why would the South be worried about Northern antislavery if the radical abolitionists were such a small part of Northern opinion? Well, by the 1850s, antislavery sentiment was pretty widespread in the North for reasons independent of anti-racism or moral objections to enslaving black people. Northerners feared "the slave power."

Since the ratification of the constitution (arguable since the colonial era), slaveholders held a disproportionate amount of power in the operation of the American federal government. The three-fifths compromise granted them disproportionate representation in the House of Representatives. 10 of the first 16 presidents were slaveholders, and there were slaveholding southerners in most presidential cabinets (I'm tempted to say "all," but am not a hundred percent confident that's the case). The first few decades of American nationhood saw north and south exist in a very fragile compromise, with policies like the Missouri Compromise (for every slave state added to the expanded nation, a free state added as well, and vice versa) designed to keep a balance of power between the free and slave states. But I'd argue, and so would many nineteenth century northerners, that the south had a decided advantage in the national power realm through most of the antebellum period.

Most white Northerners were proud to live in a democratic republic, and while they might not have cared about enslaved people as people, they understood slavery as a threat to democracy in the abstract. At the very least, it had to be contained, lest aristocratic slaveholders spread throughout the entire nation, replacing the small farms where a majority of white Americans lived and worked with massive slave labor plantations. From their miniature fiefdoms, it was feared, the "slave power" would be in full control of national policy, free to govern to their own advantage and the disadvantage of decent free working white people everywhere. Whatever the ultimate fate of slavery, its expansion had to be regulated and contained.

Which brings us to the slaveholder perspective on things. Slaveholders did not secede merely because they were offended by abolitionist rhetoric. Though they were so offended by abolitionist rhetoric that they often responded to it with brutal violence.

The Proslavery American Dream depended on the ready availability of land. A slaveholder bought land, then received credit based on the value of the land, which they used to purchase enslaved workers to grow cotton (enslaved workers produced a lot of different kinds of commodities, but cotton was the main driver of this expansion), having sold the cotton and made a profit, they could buy more land. Rinse and repeat from generation to generation and you have the proslavery vision of the future. For most of the antebellum period, land was easy to come by -- Indian removal under Jackson opened millions of acres of some of the richest soil on earth in the Southeast, the war of conquest the United States waged against Mexico gave the United States political control stretching across the continent -- but as time went on, particularly after the Mexican American war, the Northern desire to regulate slavery's growth and the southern desire to expand slavery indefinitely clashed with more intensity than they had before.

You can see how a vision of the future like that held by slaveholders would have little room for compromise. How could it? Without more land, how were younger sons supposed to support themselves and establish their own plantations? Without “diffusing” the enslaved population by spreading them out across a wider geographic area, how could they stave off the ever-present threat of apocalyptic rebellion? Never mind the fact that that last point doesn’t really make sense if you think about it, since the enslaved population would grow as it spread if trends continued.This, of course, barely touches on numerous other reasons why southerners refused to countenance a future without slavery in general: racist paranoia about a society full of free black people, fear of economic ruin, attachment to the power and prestige that slaveholding bestowed, etc. Given the mental universe that American slaveholders occupied, it's hard to see how they could rationally have been less intransigent, given that they were unwilling to see slavery end. So when Abraham Lincoln won the election of 1860 on a platform promising not to end slavery but simply to halt its expansion, they knew an existential threat when they saw one.

There's always more that can be said, but you might enjoy these older threads that touch on similar areas.

/u/sowser and others essentially discuss much of your question in Tell me if this is crazy. Could the American Civil War have been avoided by Lincoln PAYING monetary compensation to the South in exchange for no more slavery?

and /u/Georgy_K_Zhukov did Why was there a Civil War? Why could that one not have been worked out?